Hardware Reference
In-Depth Information
the SIMM in which the contacts on each side of the module are electrically
connected). See also SIMM.
Direct Rambus
Direct Rambus is the name of a third generation memory technology that offers
a completely new DRAM architecture for high-performance PCs. With Direct
Rambus data transfers are made at speeds of up to 800 MHz over a relatively
narrow 16-bit data bus compared with current SDRAM technology that operates
at 100 MHz on a relatively wide 64-bit data bus.
DIP memory
Early PCs were fitted with DRAM devices supplied in conventional dual-inline
packages (DIP). These chips were either fitted in sockets (16-or 18-pin DIL)
or permanently soldered into the system board. This type of memory is now
obsolete.
Dynamic random access memory (DRAM)
Dynamic random access memory is the most commonly used form of PC RAM.
Because of its cell architecture (in which charge is stored in a semiconductor
junction capacitance) data can only be stored for a very short time. In order to
retain the data, DRAM devices must be refreshed (i.e. read and then written
back) on a regular basis.
Dual-ported memory
See VRAM.
Extended data-output (EDO) memory
Extended data-output is a DRAM technology that shortens the read cycle
between the memory and the CPU. EDO memory allows a CPU to access
memory up to 20% faster than comparable fast-page mode (FPM) memory.
Note that EDO RAM can only be fitted to a system board that supports its use.
Enhanced synchronous dynamic random access memory (ESDRAM)
Enhanced synchronous DRAM is a type of memory that replaces expensive
SRAM in embedded systems and offers comparable speed with less power
consumption and lower cost.
Fast-page mode (FPM) RAM
Fast-page mode RAM is a technology that was used to improve the performance
of early DRAM devices. Compared with conventional page mode technology,
